How to convert a cake recipe to a different pan size

The one rule: batter follows volume

A cake recipe is really a volume of batter. Move that batter to a pan with the same capacity and nothing changes; move it to a bigger or smaller pan and you scale every ingredient by the ratio of the two capacities. That's the entire trick:

multiplier = new pan's capacity ÷ original pan's capacity

An 8″ round layer pan holds 6 cups brim-full; a 9″ round holds 8. Moving a recipe from the 8″ to the 9″ means multiplying every ingredient by 8/6 = 1.33 — 1⅓×. The 8″ and 9″ round and 9×13 capacities match Joy of Baking's pan size chart, which lists approximate brim-full volumes, and every capacity we use is pinned by an automated test.

Do it live

Pick your two pans — the converter shows both drawn to scale, the multiplier, and the time and temperature adjustments from the sections below. It handles custom sizes too.

Common conversions, worked out

These figures are computed by the same tested engine as the calculator above — they cannot drift out of sync with it.

Why time and temperature change (it's depth, not size)

Bake time doesn't track pan size — it tracks batter depth. The center of a deep layer is insulated by the batter above and beside it, so it needs longer to reach a set crumb; run the oven hot and the edges dry out first. The working rules, which the calculator applies from the actual computed depths:

• Batter noticeably deeper (more than ~20% deeper than the original): lower the oven 25°F. Increase bake time roughly 15–25% (an estimate, not a published or tested figure); start testing at the original time.
• Batter noticeably shallower (more than ~20% shallower): keep the temperature. Check 10–15% earlier than the recipe states (an estimate) — shallower batter bakes faster.
• Similar depth: keep the temperature. Bake time should be close to the original; start testing 5 minutes early. Converting between pans of similar geometry (8″ round → 9″ round with a scaled recipe) barely moves the clock.

These are the calculator's rules of thumb, not lab-tested times. "Done" is a skewer that comes out clean or with a few moist crumbs, and edges just pulling from the pan — trust those over any clock, converted or not.

Conversions to treat with care

• Angel food and chiffon → anything. These foam cakes climb the ungreased walls of a tube pan and hang upside-down to cool. In a greased round or loaf they collapse. Don't convert them; bake them in the pan they were written for.
• Anything → Bundt or tube. The center core changes how heat reaches the batter, and intricate Bundt patterns punish delicate cakes. Sturdy butter and pound cakes convert well; light sponges don't. A 10″ Bundt holds 12 cups — fill it two-thirds at most.
• Cheesecake → regular pans. You'll never get it out. Springform or a lined pan with slings only.
• Big multipliers. Past 3×, the recipe scaler warns: a recipe is only tested at its written size, and one giant bowl is harder to mix evenly. Mix in rounds of 3× or less, independent of the pan math.

Every pan we track

Capacities are brim-full. The 2″-deep 8″ and 9″ rounds and the 9×13 match Joy of Baking’s pan size chart; the methodology page gives the source for every pan. Our calculations assume a recipe fills its pan about two-thirds full.